how to data synchronization?

[AllenCoder]

  synchronized (NoteModel.class) {
                        boolean isExist = DBStore.getInstance().getNoteModelBox().count() != 0;
                        if (!isExist) {
                            DBStore.getInstance().getNoteModelBox().put(noteModel);
                        } else {
                            noteId = DBStore.getInstance().getNoteModeList().get(0).getNoteId();
                        }

                    }

Many times, I have some insert and update operations, however, because only the id is guaranteed to be unique. I insert, you need to determine whether it already exists, if there is updated, but found that the concurrent operation, it will lead to repeated data insertion

[greenrobot]

You need to use transactions. So your example should look something like this:

boxStore.runInTx()( new Runnable() {
    public void run() {
        boolean isExist = DBStore.getInstance().getNoteModelBox().count() != 0;
        if (!isExist) {
            DBStore.getInstance().getNoteModelBox().put(noteModel);
        } else {
            noteId = DBStore.getInstance().getNoteModeList().get(0).getNoteId();
        }
   });

[AllenCoder]

thank you very much!!!